PURPOSE: A sterilizing fiber sheet having sterilizing ability sufficiently usable for water treatment system, air-conditioning system, etc., having sterilizing ability for a long period, obtained by immobilizing a lytic enzyme having sterilizing ability to the fiber surface of nonwoven fabric.

CONSTITUTION: A lytic enzyme having sterilizing ability is immobilized to the fiber surface of nonwoven made by using natural fiber or chemical fiber or blended fiber of them by immobilization treatment such as carrier bonding, crosslinking, inclusion process, etc. The carrier bonding, for example, is carried out by treating nonwoven fabric of 100% nylon with hydrochloric acid, processing the fiber surface into a diazonium derivative, immobilizing an enzyme to it by diazo coupling. The crosslinking is done by treating the surface of nonwoven fabric consisting of 100% nylon fiber with hydrochloric acid, subjecting an enzyme to carrier crosslinking with glutaraldehyde.